John H. Purk is a practicing general dentist. Since 1983 he has taught Operative Dentistry full time at UMKC School of Dentistry. In 2002, he completed an Indisciplinary PhD in Oral Biology/Engineering. His dissertation was an in-vivo clinical research study. His immediate goal is to develop into an independent clinical researcher who can design, organize, characterize the dentin adhesive interface, and conduct clinical research. His long term goal is to train young investigators how to conduct clinical research and conduct translational research. This application is divided into two areas;research career development plan (didactic) and clinical research project. The first didactic component will provide coursework that includes clinical research training in the designing, implementing, analysis and assessment of clinical trials stressing the importance of epidemiology, biostatistics and analysis of data. Additional coursework in micro-Raman spectroscopy in order to characterize the infiltration of the adhesive resin at the adhesive-dentin (a/d) interface will be undertaken. The second didactic experiential component is intended to help the principal investigator observe how didactic information is integrated into an ongoing clinical research project at a study center and also for the principal investigator to set up an in-vitro lab which can simulate positive pulpal pressure to simulate in-vivo conditions. These courses and experiences will allow the candidate to develop independence and expertise in designing and conducting simulated in-vivo and clinical research. The research part combines 1. a preliminary in-vitro pilot study and 2. an in-vivo pilot evaluation of a new emerging low shrink/low stress siloxirane adhesive system for the restoration of interproximal caries in the permanent teeth of children and adults. An in-vitro mechanical and morphologic analyses of these in-vivo restorations following their extraction will also occur. The candidate will develop a unique database for the new dental adhesive composite system that includes clinical features e.g. post-op sensitivity, microtensile bond strength, quantitative information on resin infiltration and void formation at the (aid) interface. The analysis of this data will provide critical, new data on changes within the (a/d) interface which will help researchers evaluate the biomaterials science, and the polymerization and stress properties of a new emerging low shrink/low stress siloxirane adhesive technology. The overall hypotheses of this project are that the clinical performance of class II composite restorations placed in permanent premolars depends on the development of a satisfactory bond at the gingival margin and that a new low shrink/low stress dentin adhesive and resin composite will result in a superior bond at the gingival margin of the class II resin composite restoration. The specific aims will test the following hypotheses: A new low shrink/low stress adhesive siloxirane resin adhesive system compared to a traditional Bis-GMA resin composite system will have a greater microtensile bond strength and adhesive penetration to the gingival wall of class II composite restorations and less void formation at the (a/d) interface.